Error in loading model
The line p_bone=pose.bones[b.name] is giving the error key "" not found. The two quotes after key indicate that b.name is an empty string which is not a key in the pose.bones dictionary.

That might indicate that one of the bones does not have a name, it could also indicate that a bone has an unusual or non-text character that is causing an error when reading it into a string.

Another possibility is a zero sized bone, blender doesn't retain bones that have zero length, this means as the bone was initially created blender deleted it and then when it was referenced again later you get an error.